The present invention relates to the repair and reconditioning of buried conduits, such as sewage lines, drainage lines, and the like. More particularly, the present invention relates to the repair and reconditioning from a remote location of buried conduit systems having branching connections between conduits.
In the past, it has been common to use masonry and clay conduits buried in the ground to construct sewage systems, drainage systems, and the like. Although these buried conduits have been quite satisfactory for their purpose, it has been found that over a period of time, these conduit systems can deteriorate or become damaged. This deterioration can be as a result of many causes such as, root action, soil movement, deterioration of the pipe material, and the like. The conventional method of repairing buried conduit systems is to completely excavate the system and repair the damaged portions thereof. The disadvantage of this conventional repair method is apparent when it is considered that the systems are commonly positioned under a street or roadway, and are buried in the ground from 6 to 30 feet. Thus, substantial expenses can be involved in excavation and repair under these conditions.
In addition, when the systems are located below roadways and other structures, excavation requires that these structures be disturbed and repaired. In addition, this method can require substantial periods of time, and during this time, use of the sewage system and the roadways is prevented.
To overcome the disadvantages of the excavation method of repairing and reconstructing buried conduits, a method wherein a flexible liner of suitable material is axially inserted into the main from a convenient access point has been used. In this method, a liner can be pushed through a length of the main to another point where the access to the main is convenient spanning distances up to 1500 ft. In some situations, convenient access to the main can be obtained at existing manholes, or the like. In other situations, excavation at spaced locations along the length of a sewage main is required. Once access is obtained, the main is cleaned and lengths of polyethylene liner can be axially inserted into the main.
This method of inserting a liner has been found to be quite satisfactory in repairing sections of main which do not have lateral service conduits connected thereto, but has been undesirable in repairing systems where a plurality of service access conduits are connected to and extend from the central main. This is a result of the fact that heretofore, there was no satisfactory method for connecting a service conduit to a main at a remote buried location without additional excavation at the connection of the service conduit to the main.
Therefore, a great need exists for a method and apparatus of interconnecting and sealing two conduits of a system at a remote buried location without excavation at the intersection.
In addition, it is desirable that the connections be made at a distance of at least 25 feet from the main to eliminate the necessity of excavating the roadway. It is important that the resulting connection be leakproof to prevent both infiltration and exfiltration of the system. The method and apparatus must be able to work in a dirty, wet environment of systems such as an active sewer without requiring substantial excavation of or interference with the use of the roadway. It is desirable that the method be easy to practice and it is preferable that it be usable in situations where the lateral service conduit is relined or when the lateral is not relined. The required equipment must be portable and adaptable to a wide variety of situations.
Therefore, according to one aspect of the present invention, an improved method for forming a sealed connection between two conduits at a remote buried location is provided which can be performed without the necessity of excavation in the area of the connection. According to another aspect of the present invention, improved apparatus are provided for use in forming a sealed connection between two conduits at a buried remote location.
More particularly, according to the present invention, an improved method and apparatus is provided for repairing a conduit system, such as a sewer system, having a buried main and at least one branching service conduit connected to the main. According to the improved method, access is gained to the buried main at spaced locations which are remote from the intersection of the service line and the main. The service line is also opened at a spaced location. Thereafter, the main and service line are cleaned. A length of polyethylene liner is axially inserted into the main through the area of the connection with the lateral service conduit. Thereafter, an improved dispenser is axially inserted through the length of the service conduit to a point adjacent to the main. A foamable setting resinous material, preferably a foamable setting synthetic polymer and more preferably a foamable thermosetting plastic is dispensed in the annulus formed between the liner and the main in the area of intersection with the service conduit. Materials which are preferred in the practice of the present invention include polyurethane foams, acrylamide foams and elastomer foams with the particular preferred material being polyurethane foams.
An improved cutter is axially moved through the length of the service conduit to form a port through the resinous material and the wall of the liner to connect the service conduit and the liner of the main. Thereafter, a sealing material can be dispensed in the area of the connection to coat the resinous material. Thus, a sealed interconnection is provided.
In another embodiment, the service conduit is also lined with a polyethylene conduit. The annular spaces between the liners and the respective service conduit and main is filled with a foamable setting resin in the area of intersection. Thereafter, a port is formed in the above-described manner to form a sealed connection between the two lines.